Add nav

style.css

@@ -23,6 +23,28 @@ header
     float: right;
 }
 
+nav { text-align: center; }
+
+nav ul { list-style-type: none; }
+
+nav li
+{
+    display: inline-block;
+
+    border: 2px solid;
+    padding: 5px;
+    margin-right: 10px;
+}
+
+nav li a
+{
+    color: orange;
+    text-decoration: none;
+}
+
+nav li:hover{ box-shadow: 10px 10px 0px black; }
+
+
 #introduction, #hello
 {
     text-align: justify;
@@ -174,4 +196,4 @@ form.invalidation input
 tbody tr:hover .tooltip
 {
     display: block;
-}
+}